feat: introduce get prompt from static files

packages/spacecat-shared-utils/src/helpers.js

@@ -12,6 +12,7 @@
 
 import { Parser } from '@json2csv/plainjs';
 import { GetSecretValueCommand, SecretsManagerClient } from '@aws-sdk/client-secrets-manager';
+import { promises as fs } from 'fs';
 import { isString } from './functions.js';
 
 /**
@@ -110,3 +111,23 @@ export function replacePlaceholders(content, placeholders) {
     }
   });
 }
+
+/**
+ * Reads the content of a prompt file asynchronously and replaces any placeholders
+ * with the corresponding values. Logs the error and returns null in case of an error.
+ *
+ * @param {Object} placeholders - A JSON object containing values to replace in the prompt content.
+ * @param {String} filename - The filename of the prompt file.
+ * @param {Object} log - The logger
+ * @returns {Promise<string|null>} - A promise that resolves to a string with the prompt content,
+ * or null if an error occurs.
+ */
+export async function getPrompt(placeholders, filename, log = console) {
+  try {
+    const promptContent = await fs.readFile(`./static/prompts/${filename}.prompt`, { encoding: 'utf8' });
+    return replacePlaceholders(promptContent, placeholders);
+  } catch (error) {
+    log.error('Error reading prompt file:', error.message);
+    return null;
+  }
+}

packages/spacecat-shared-utils/src/index.d.ts

@@ -152,6 +152,19 @@ declare function generateCSVFile(data: object[]): Buffer;
  */
 declare function replacePlaceholders(content: string, placeholders: object): string;
 
+/**
+ * Reads the content of a prompt file asynchronously and replaces any placeholders
+ * with the corresponding values. Logs the error and returns null in case of an error.
+ *
+ * @param {Object} placeholders - A JSON object containing values to replace in the prompt content.
+ * @param {String} filename - The filename of the prompt file.
+ * @param {Object} log - The logger
+ * @returns {Promise<string|null>} - A promise that resolves to a string with the prompt content,
+ * or null if an error occurs.
+ */
+declare function getPrompt(placeholders: object, filename: string, log: object):
+  Promise<string|null>;
+
 /**
  * Retrieves stored metrics from S3.
  * @param config - Configuration object

packages/spacecat-shared-utils/test/helpers.test.js

@@ -15,12 +15,14 @@
 import { expect } from 'chai';
 
 import nock from 'nock';
+import { promises as fs } from 'fs';
+import sinon from 'sinon';
 import {
   generateCSVFile,
   resolveSecretsName,
   resolveCustomerSecretsName,
   getRUMDomainKey,
-  replacePlaceholders,
+  replacePlaceholders, getPrompt,
 } from '../src/helpers.js';
 
 describe('resolveSecretsName', () => {
@@ -227,3 +229,52 @@ describe('replacePlaceholders', () => {
     expect(result).to.equal('Hello, John! You are {{age}} years old.');
   });
 });
+
+describe('getPrompt', () => {
+  let readFileStub;
+  let logStub;
+
+  beforeEach(() => {
+    readFileStub = sinon.stub(fs, 'readFile');
+    logStub = { error: sinon.stub() };
+  });
+
+  afterEach(() => {
+    sinon.restore();
+  });
+
+  it('reads the prompt file and replace placeholders', async () => {
+    const placeholders = { name: 'John' };
+    const filename = 'test';
+    const fileContent = 'Hello, {{name}}!';
+    readFileStub.resolves(fileContent);
+
+    const result = await getPrompt(placeholders, filename, logStub);
+
+    expect(result).to.equal('Hello, John!');
+    expect(readFileStub.calledOnceWith(`./static/prompts/${filename}.prompt`, { encoding: 'utf8' })).to.be.true;
+  });
+
+  it('returns null and log an error if reading the file fails', async () => {
+    const placeholders = { name: 'John' };
+    const filename = 'test';
+    const errorMessage = 'File not found';
+    readFileStub.rejects(new Error(errorMessage));
+
+    const result = await getPrompt(placeholders, filename, logStub);
+
+    expect(result).to.be.null;
+    expect(logStub.error.calledOnceWith('Error reading prompt file:', errorMessage)).to.be.true;
+  });
+
+  it('handles empty placeholder object and return content as is', async () => {
+    const placeholders = {};
+    const filename = 'test';
+    const fileContent = 'Hello, {{name}}!';
+    readFileStub.resolves(fileContent);
+
+    const result = await getPrompt(placeholders, filename, logStub);
+
+    expect(result).to.equal('Hello, {{name}}!');
+  });
+});